Frogs and Toads of Illinois

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Frogs

True Frog Family – Ranidae

The True Frogs are your typical frogs that you find along the shores of a lake or pond.

American Bullfrog (Rana catesbeiana)

Common Name: American Bullfrog
Scientific Name: Rana catesbeiana
Location: Statewide
Breeding Season:

The American Bullfrog is the largest native frog in the United States. There is no dorsal ridge that runs down its back on the American Bullfrog. This is the distinguishable characteristics of the frog.

Green Frog (Rana clamitans)

Common Name: Green Frog
Scientific Name: Rana clamitans
Location: Statewide besides southcentral Illinois
Breeding Season:

The Green Frog looks very much like the American Bullfrog but it’s a tad smaller. It has a dorsal ridge that runs down its back but they are incomplete and do not reach all the way.

Wood Frog (Rana sylvatica)

Common Name: Wood Frog
Scientific Name: Rana sylvatica
Location: Near the northern, eastern, and southern borders of the state
Breeding Season:

The Wood Frog is one of the most widespread frog in the United States but it’s a little rare in Illinois. It’s listed by the states as a Species in Greatest Need of Conservation. It’s fairly easy to distinguish because of it’s mask around it’s eyes.

Common Name: Crawfish Frog
Scientific Name: Rana areolatus
Location: Southern part of the state
Breeding Season:

The Crawfish Frog gets its name from living in crawfish holes. Its has skin folds on the side and a small typanum. It also has a pair of vocal sacs for calling.

Common Name: Plains Leopard Frog
Scientific Name: Rana blairi
Location: Everywhere besides the northern border
Breeding Season:

Northern Leopard Frog (Rana pipiens)

Common Name: Northern Leopard Frog
Scientific Name: Rana pipiens
Location: Northern part of the state
Breeding Season:

Common Name: Southern Leopard Frog
Scientific Name: Rana sphenocephalus
Location: Southern half
Breeding Season:

The Southern Leopard Frog has a white spot on its tympanum which can help differentiate the species from the other two. The Plains Leopard Frog is different from the Southern and Northern Leopard Frog because of its dorsal ridge. The Plains Leopard Frogs has a break and an indent near its butt while the North and South Leopard Frog just has a straight line.

Common Name: Pickeral Frog
Scientific Name: Rana palustris
Location: Northern and western borders of the state
Breeding Season:

Pickeral Frog looks like the leopard frogs but its spots are more rectangular than the leopard frogs.

Tree Frog Family – Hylidae

Cricket Frogs – Acris

Common Name: Blanchard’s Cricket Frog
Scientific Name: Acris blanchardi
Location: Statewide
Breeding Season:

The Blanchard’s Cricket Frog is the only cricket frog in the state. Its skin is relatively more rough than the other tree frogs in the state. It also has no distinct markings.

Tree Frogs – Hyla

Eastern Gray Tree Frog (Hyla versicolor) and Cope’s Gray Tree Frog (Hyla chrysoscelis)

Common Name: Eastern Gray Tree Frog
Scientific Name: Hyla versicolor
Location: Everywhere besides southern tip
Breeding Season:

These two frogs are identical besides their calls and chromosome numbers. Note that Gray Tree Frogs are not always gray and can be green. They have yellow or orange coloration on their back legs which is nice to identify them.

Here is a short video of a few Eastern Gray Tree Frog calling

Common Name: Cope’s Gray Tree Frog
Scientific Name: Hyla chrysoscelis
Location: Statewide
Breeding Season:

Common Name: Bird-Voiced Tree Frog
Scientific Name: Hyla avivoca
Location: Southern tip of the state
Breeding Season:

The Cope’s Gray Tree Frog, the Eastern Gray Tree Frog and the Bird-Voiced Frog look very much a like. The difference is the coloration on the inner thigh. Cope’s Gray Tree Frog and Gray Tree Frog has brighter orange color on the thigh while the Bird-Voiced Frog is more greenish-yellow.

Common Name: Green Tree Frog
Scientific Name: Hyla cinerea
Location: Southern tip of the state
Breeding Season:

The Green Tree Frog does not have any coloration on its inner legs. It has a white line that runs down its side.

Chorus Frogs – Pseudacris

Spring Peeper (Pseudacris crucifer)

Common Name: Spring Peeper
Scientific Name: Pseudacris crucifer
Location: Statewide
Breeding Season:

The Spring Peeper is a notoriously loud frog and one of the first signs of spring. It has a noticeable X marking on its back.

Boreal Chorus Frog (Pseudacris maculata)

Common Name: Boreal Chorus Frog
Scientific Name: Pseudacris maculata
Location: Statewide besides the southern tip
Breeding Season:

The Boreal Chorus Frog’s middle stripe on its back is occasionally broken. It also has really small legs.

Common Name: Western Chorus Frog
Scientific Name: Pseudacris triseriata
Location: Southern half
Breeding Season:

The Western Chorus Frog’s three stripes on its back are rarely broken.

Common Name: Upland Chorus Frog
Scientific Name: Pseudacris feriarum
Location: Southern tip
Breeding Season:

The Upland Chorus Frog’s stripes on it’s back are often broken up and can appear as spots.

Common Name: Illinois Chorus Frog
Scientific Name: Pseudacris illinoensis
Location: Western border area
Breeding Season:

The Illinois Chorus Frog does not have a white line that extends off the lips while the other chorus frogs do.

Toads

True Toad Family – Bufonidae

The family Bufonidae is known for the toxins / poison they produce called Bufotoxins. It is a bad idea to try to eat these guys.

American Toad (Anaxyrus americanus)

Common Name: American Toad
Scientific Name: Anaxyrus americanus
Location: Statewide
Breeding Season:

Common Name: Fowler’s Toad
Scientific Name: Anaxyrus fowleri
Location: Everywhere besides the northern border
Breeding Season:

The American Toad and Fowler’s Toad look fairly similar. The Fowler’s Toad has their cranial crest and the parotoid gland touch while the American Toad’s cranial crest and parotoid gland do not touch or are connected by a spur. The American Toad has a more speckled belly while the Fowler’s Toad has a clear, white one.

Spadefoot Toads – Scaphiopodidae

Common Name: Eastern Spadefoot Toad
Scientific Name: Scaphiopus holbrookii
Location: Southern tip
Breeding Season:

The Eastern Spadefoot Toad is the only Spadefoot toad in the state so it can easily be identified because of the spade on its back legs.

Narrowed Mouth Toad Family – Microhylidae

Common Name: Eastern Narrow Mouthed Toad
Scientific Name: Gastrophryne carolinensis
Location: Southern tip
Breeding Season:

The Eastern Narrow Mouthed Toad is the only narrow mouthed toad in the state. One could potentially misidentify it has a Spadefoot toad because of its burrowing lifestyle but the head is narrower and there’s no spade on the back feet.